In an organic EL (electroluminescent) lighting panel used in an organic EL lighting device, a transparent electrode formed of ITO, ZnO, SnO2 (Nesa glass), or the like is generally used as an anode. Such a transparent electrode has a high volume resistivity, and thus exhibits a high sheet resistance when it is formed into a thin film. Accordingly, in the organic EL lighting panel using the above-described transparent electrode, the wiring resistance increases as the distance from an end of the transparent electrode (a power feed terminal to which electric power is supplied from a power source) increases, i.e., the wiring resistance increases from the end toward the inside (toward the central portion) of the organic EL lighting panel, so that voltage drop is more liable to occur. The voltage drop in the electrode section causes power loss in this section, and at the same time, decreases the luminance and chromaticity, thereby deteriorating the uniformity in luminance and chromaticity in a plane of an organic EL lighting panel. The above-described decrease in the luminance and chromaticity occurs for the following reason. An organic EL element is an element that emits light utilizing electroluminescence. Owing to the voltage drop, the electric field at the central portion of the element becomes lower than that in the vicinity of the power feed terminal. This lowers the injection efficiency of carriers (holes and electrons), whereby the light emission efficiency is lowered.
Under these circumstances, it has been proposed to provide an auxiliary electrode on a transparent electrode in order to lower the wiring resistance on the transparent electrode side (see Patent Document 1, for example).